This invention relates to foam cushions, and more particularly to foam cushions with improved dynamic resistance characteristics.
Fragile articles, such as electronic equipment and the like, must be packaged properly during shipment to prevent damage to the articles. The package must support its contents in the static condition, when it is stationary, and must absorb a substantial portion of external forces which may be exerted on the package if it is jostled or dropped. The ability of the package to absorb such external forces may be expressed as its dynamic resistance characteristic.
Various forms of plastic materials may be used to package fragile articles. Plastic beads may be placed around the article by covering the bottom of a container with beads, placing the article to be shipped on the beads in the center of the container, and filling the rest of the container with beads. A substantial amount of plastic is used, however, and if the article is not correctly placed in the container, or if the beads shift in the container, there may not be enough beads on a particular side of the package, which could result in damage to the article. Also, the beads and all related equipment must be stored and maintained near the packing area, and the packages cannot be prepared in advance of shipment. These conditions are inefficient, especially on assembly lines, and may reduce productivity and delay shipments. In addition, the beads are often discarded after shipment, and are not reused.
The plastic beads may be loosely encased in a plastic sack as described in U.S. Pat. No. 3,462,007. Air escapes from the sack through perforations so that the article is cushioned by the beads.
The quantity of plastic used in packaging may be reduced substantially by using pieces of flexible foam material instead of beads. However, as the quantity of plastic is reduced, the amount of force which it will absorb, or its dynamic resistance characteristic, decreases. Several foam structures have been developed which increase the dynamic resistance characteristic of foam, as seen in U.S. Pat. Nos. 3,607,601, 3,954,537, 4,062,712, 4,147,825 and 3,345,245. However, these structures include more than one layer of foam material, which requires relatively substantial fabrication machinery and techniques. Thus, there is a need for foam structures which package articles with a minimum amount of plastic and relatively simple fabrication machinery and techniques, and have an improved dynamic resistance characteristic.
One or more foam structures may be used in connection with a container to package an article. U.S. Pat. Nos. b 3,602,376, 3,690,540, 3,173,535, 3,275,131 and 3,471,116 describe various packages which use foam plastic or the like to package articles. However, none of the patents describe packages which have an improved dynamic resistance characteristic. Thus, there is a need for packages which use foam plastic or the like and have an improved dynamic resistance characteristic.
Accordingly, an object of the present invention is to provide new and improved packages and structures for packaging.
Another object is to provide new and improved foam cushions for packaging articles which use a reduced quantity of reusable plastic and may be relatively easily fabricated.
Yet another object is to provide new and improved packages which use a reduced quantity of reusable plastic and have an improved dynamic resistance characteristic.
In keeping with one aspect of the invention, a plurality of cushions are secured inside of a packing container in a pre-determined array. Each cushion has a piece of flexible foam material and a pliable plastic cover which contiguously surrounds the cushion on all sides. The bottom surface of the cushion may also be covered, if desired, and a lip may be provided on the cover to secure the cushion to the container. A plurality of air vents are provided in the cover near the lip to control the flow of air from the cushion when the foam is compressed.